Vol 18, No 5 (2022)

Analysis and design of building structures

Physical and mechanical properties of pre-bound aggregate composites

Erofeev V.T., Kaznacheev S.V., Pankratova E.V., Seleznev V.A., Tyuryahina T.P.


New building materials and products in construction and reconstruction, which improve the performance and efficiency characteristics of buildings, reduce material consumption, cost and labor intensity, are always relevant. A promising direction for further development of composite materials is the employment of pre-bound aggregate materials. Their production is a two-stage process, which involves at first creating an optimal aggregate mix and gluing the grains to each other and secondly filling the voids of the obtained aggregate framework with a high-workability matrix. Presented research is an experimental investigation of physical and technical properties of pre-bound aggregate composite materials. Composites with complex binders are also considered in this study. In such cases, the aggregate framework and the grouting matrix were made of binders of different nature, which are incompatible when the components are mixed ordinarily. When studying composites, a complex of physical and mechanical methods was used. Improvement of physical and mechanical properties of framework composites in comparison with composites obtained according to conventional techno- logy has been established. These advantages are identified primarily for such properties as deformability, impact strength, creep.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):399-406
pages 399-406 views

Justification of the parameters of regulationof forces for steel-reinforced concrete span structures from project “43282 km” by TSNIIPSK

Belutsky I.Y., Kudryavtsev S.A., Lazarev I.V.


Steel-reinforced concrete spans in road bridges have been widely used since the late 1950s, in the configuration of large-span bridges built across significant water barriers. To date, the issue of the need to reconstruct such span structures, including those designed and built according to the project “43282 km” developed by TsNIIPSK, is becoming increasingly relevant. The authors analyze the stages of the production of works of a particular object, developed for the implementation of the entire complex of works on its reconstruction using the method of force regulation. The presented order of work was successfully implemented during construction of the bridge over Kabarga River in Primorsky Krai. This made it possible to preserve the existing structure of the span (main beams and braces), replacing the worn-out reinforced concrete slab with a new - metal orthotropic one, while ensuring that the conditions of strength and stability of the flexural-torsional shape of solid-walled beams are met, in the process of dismantling the existing roadway slab and constructing a new one. Considering that steel-reinforced concrete bridges are built across large water barriers and have a very significant cost due to their large length, reconstruction using existing supports can significantly reduce the cost of construction, so, the possibility of upgrading the existing steel-reinforced concrete span structure is, undoubtedly, relevant. Based on the structural and technological measures presented by the authors, it is possible to carry out and effectively implement work on the reconstruction of the existing steel-reinforced concrete bridges that do not fully meet modern requirements for load capacity and throughput.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):407-416
pages 407-416 views

The influence of bracing on the stress state of the ribbed-ring dome framework

Lebed E.V.


The aim of current research was to establish the relationship between the stress state of the ribbed-ring dome framework and the degree of its bracing. It was assumed that the meridional ribs and rings of the dome framework are made of metal. The framework of the dome consists of 24 ribs and 7 rings. The study was performed for a ribbed-ring dome of spherical shape with a span of 39.3 m and a height of 11.0 m on computer models. The initial computer model of the framework of a ribbed-ring dome made of steel I-beams without bracing has been developed. On the basis of the initial model, additional models were developed for the frameworks with bracing between meridional edges in four, eight cyclically symmetric sectors and in all sectors. Both for the initial model and for all models of the dome framework with bracing, computer calculations were performed for the effect of the load from the own weight of the load-bearing and enclosing structures, and two variants of the snow load. During the calculations, deformations, internal forces and stresses in the meridional ribs, upper and intermediate rings of different models were determined, which were compared with each other. Graphs of changes in deformations of the frame, graphs and diagrams of changes in internal forces and stresses in the meridional ribs, in the upper and intermediate rings of the dome, depending on the degree of bracing in the framework, are obtained. An assessment of the influence of bracing on the stress state of the rib-ring dome frame is performed. The peculiarities of the influence of different coupling schemes on the stressed state of the dome frame are noted.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):417-427
pages 417-427 views

Peculiarities of the condition of the foundation slab of the pumped storage power plant water intake

Lisichkin S.E., Kotitsyna S.S.


The authors present the results of the analysis of field observations of the condition of the base slab of the water intake structure of hydroelectric power plant (including the stresses in the reinforcement in the areas of intersection with the vertical joints and the width of the opening of these joints). The aim of the study is to control the condition of the reinforced concrete structure of the foundation slab of the water inlet of the hydroelectric power plant, as well as to develop measures to strengthen the bottom section of the foundation slab in the areas of vertical interblock joints. In order to control the stress and strain of the base plate of the water intake of hydroelectric power plant, string control and measuring equipment was installed: on reinforcement rods - reinforcement dynamometers PSAS, on vertical interblock joints - displacement sensors PLPS. The field observations of the stress state of the reinforcement of the base slab of the water intake structure of hydroelectric power station showed that high values of tensile stresses, exceeding the design resistance of A500C class reinforcement (435 MPa), occurred in the reinforcement rods (directed along the flow), crossing the lower vertical interblock joints. There was also fixed the width of opening of the vertical interblock joint, reaching 1.28 mm. There was a necessity to strengthen the lower section of the foundation slab of the water intake structure of hydroelectric pumped storage power plant. For this purpose, inclined reinforcing bars (anchors) crossing the lower vertical interblock joints were installed. The outlet sections of the buttresses of the slab of the downstream section of the inlet to the downstream parapet were increased.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):428-437
pages 428-437 views

Analytical and numerical methods of analysis of structures

Predicting the residual life of concrete structures in biocorrosion from the position of the theory of mass transfer

Fedosov S.V., Loginova S.A., Shalygina A.A.


The problem of corrosive destruction of concrete and reinforced concrete structures of industrial buildings affected by aggressive environments does not lose its relevance, because, despite the abundance of modern methods of protection, there are still no radical methods of corrosion control. Corrosive destruction of building materials leads to a strength and load-bearing capacity reduction, loss of aesthetic properties of concrete and reinforced concrete structures and, consequently, to a decrease in the residual life of buildings and structures. The biological factor often acts as an intensifier of corrosive destruction. In this regard, it is reasonable to search for the possibility of predicting the durability of concrete and reinforced concrete structures in aggressive liquid mediums, taking into account the biofactor effect from the standpoint of mass transfer theory. The authors present a model of mass transfer in a concrete structure exposed to aggressive environment and biofouling. The proposed physical and mathematical model considers the properties of concrete and aggressive environment, as well as the kinetics of continuous processes of growth, reproduction and death of microorganisms. The results of numerical experiments on the proposed mathematical model are provided. The application of the received solutions will allow timely monitoring of biocorrosive destruction of concrete and reinforced concrete structures and selecting effective methods of protection.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):438-443
pages 438-443 views

Influence of the soil base on the stress-strain state of a large-span building with a cylinder-and-slab roof

Kuzhakhmetova E.R., Sutyrin V.I.


The authors consider finite element models of a large-span building with a cylinder-and-slab roof as a large spatial mechanical system with different boundary conditions. The first model represents the superstructure of the building with a fixed-end at the soil base level. In the second model, the superstructure is based on the substructure, which includes a pile foundation and a soil base with different physical and mechanical properties. The purpose of the study is a comparative numerical analysis of the stress-strain state of a large-span building with different boundary conditions. The numerical study revealed the influence of the structural features of the substructure of the building, as well as the physical and mechanical properties of the soil base on the stress-strain state of the long-span roof and the building as a whole. Numerical static analysis of spatial finite element models of a large-span building was carried out in the СAE class Femap NX Nastran software package. The results of the static analysis demonstrated a significant structural influence of the substructure of a large-span building on the characteristics of its stress-strain state. In the next article, it is proposed to conduct a modal analysis for these building models.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):444-457
pages 444-457 views

Geometrical modeling of shell forms

Analytical surfaces for architecture and engineering

Gil-Oulbé M., Daou T., Mariko O.


Geometers have proposed more than 600 analytical surfaces for implementation. The largest number of these surfaces is used in architecture and mechanical engineering. Although digital architecture and free form architecture are now increasingly influencing the design of long-span shell structures and curved buildings, the research and application of analytical surfaces continues on an increasing scale. The purpose of the research is to study the state of affairs in the application of analytical surfaces in the construction and engineering industries and to clarify the classes of surfaces that have found application in the study of physical phenomena or in solving purely mathematical problems, but not used in other areas of human activity. Another goal is to find analytical surfaces promising for application in architecture and mechanical engineering, which are still little known to architects and engineers. It has been established that, as before, designers take new analytical surfaces to implement their creative ideas from well-studied classes of surfaces of revolution, transfer and umbrella, minimal, ruled, wavy surfaces.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):458-466
pages 458-466 views

Surface parameterization complex geometry

Yakupov S.N., Nizamova G.K.


Among thin-walled structures, including building structures and constructions, shells of complex geometry are effective in their rigidity and strength characteristics, which are also distinguished by architectural harmony. For a wider application of shells of complex geometry, it is necessary to reliably assess their stress-strain state. In this case, an integral part of the calculation is the parametrization stage of the median surface of shells of complex geometry. There are shells of complex geometry of canonical and non-canonical forms. For shells of non-canonical shape, the median surface cannot be defined by analytical formulas. At the same time, difficulties arise at the stage of specifying (parameterizing) the shape of the median surface. The task becomes more complicated when the shell fragment has a complex contour and one or more surface points have fixed coordinates. For building structures, this is, for example, the presence of additional internal supports. Information about the spline version of the FEM is presented. Some well-known parametrization methods are noted. The approach of parametrization of a minimal surface of a complex shape bounded by four curved contours and a given (fixed) coordinate of one inner point of the surface is considered. An algorithm for constructing a spatial network, as well as determining coordinates, metric tensor components and Christoffel symbols necessary for solving parametrization problems in the spline version of the finite element method is described.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):467-474
pages 467-474 views

Experimental researches

Couplings slip determination of the threadbar of strength class 500 N/mm2

Grishin G.E., Tikhonov G.I., Savrasov I.P., Okolnikova G.E.


The authors present the results of R&D on the topic of coupling slip of threadbar of class Av500P. The aim of the work was to obtain experimental data to study the effect of the threadbar coupling on the slip (deformability) of the joint and taking into account the characteristics of the joint in the design of structures. The strength and deformability of coupling samples of threadbar with a diameter of 16, 25 and 40 mm with an innovative four-sided (four-row) thread profile of class Av500P have been studied in accordance with the methodology of international and Russian standards. The samples were made with different tightening torques of the lock nuts and anchor-adhesive compositions inside the coupling. Along with the results of the study, it can be concluded that these couplings of innovative four-row threadbar of class Av500P meet the requirements of international and Russian standards when applying a certain tightening torque to the tightened lock nuts, depending on the diameter of the fittings to be joined and the use of anchor-adhesive compositions on large and medium diameters of the threadbar to be joined. The diagrams of thread joints obtained during the experiment can be used in design practice when design reinforced concrete structures according to the deformation model. Together, this makes it possible to introduce thread joints into the Russian construction regulatory code.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(5):475-484
pages 475-484 views

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